Basically a nice way of saying "parking duty". These usually consist of lazy or fat cops who don't have what it takes to be a real cop onpatrol. These are usually the little bastards that give you parking tickets because it is pretty much their only jurisdiction.

Wife; How was work?
Husband; Good
Wife; What'd you do? Did you get any arrest?
Husband; Yeah, I arrested someone for stealing a traffic cone.
Wife; That's lame
Husband; Honey I was on parking enforcement though because I don't have what it takes to be a real cop.
Wife; That's alright, you've already proved in the bedroom that you didn't have what it takes.
Husband; !!!!!